Objective Serving Royal Canadian Mounted Police (RCMP) have screened positive for one or more mental disorders based on self-reported symptoms with substantial prevalence (i.e., 50.2%). Mental health challenges for military and paramilitary populations have historically been attributed to insufficient recruit screening; however, cadet mental health when starting the Cadet Training Program (CTP) was unknown. Our objective was to estimate RCMP Cadet mental health when starting the CTP and test for sociodemographic differences. Method Cadets starting the CTP completed a survey assessing self-reported mental health symptoms (n = 772, 72.0% male) and a clinical interview (n = 736, 74.4% male) with a clinician or supervised trainee using the Mini-International Neuropsychiatric Interview to assess current and past mental health. Results The percentage of participants screening positive for one or more current mental disorders based on self-reported symptoms (15.0%) was higher than the diagnostic prevalence for the general population (10.1%); however, based on clinical interviews, participants were less likely to screen positive for any current mental disorder (6.3%) than the general population. Participants were also less likely to screen positive for any past mental disorder based on self-report (3.9%) and clinical interviews (12.5%) than the general population (33.1%). Females were more likely to score higher than males (all ps<.01; Cohen's ds .23 to .32) on several self-report mental disorder symptom measures. Conclusions The current results are the first to describe RCMP cadet mental health when starting the CTP. The data evidenced a lower prevalence of anxiety, depressive, and trauma-related mental disorders than the general population based on clinical interviews, contrasting notions that more rigorous mental health screening would reduce the high prevalence of mental disorders among serving RCMP. Instead, protecting RCMP mental health may require ongoing efforts to mitigate operational and organizational stressors.